1. Field of the Invention
The present invention relates to a provision of mechanical protection for a Tape Automated Bonding (TAB) device mounted on a flexible printed circuit board (PCB) during assembly and life. For the purpose of the following description and claims, a TAB device refers to a TAB or similarly delicate electrical device assembly.
2. Prior Art
Such protection has additional heat conducting properties to assist heat dissipation from the TAB device. A problem associated with a flexible electrical assembly including a TAB device concerns mechanical failure of delicate, electrical between the flexible circuit board and the device. These connections can be easily damaged or broken during post manufacturing processes in which the flexible characteristic of the flexible electrical assembly is not restrained. Similar breakages can also occur where the flexible characteristics of such an assembly are exercised as part of the normal installation and operation of a product.
Another problem associated with a flexible electrical assembly including a TAB device concerns the removal of heat
energy generated by the TAB device whilst retaining the flexible characteristic of the flexible electrical assembly.
EPA103067 describes a method by which a multiplicity of integrated circuit modules mounted on flexible circuit board can be cooled. The modules are orientated so that the top surface of each makes contact with a common planar surface which is part of a cooling plate. A coefficient of thermal conductivity between the cooling plate and each module is minimised by maximising associated areas of contact with thermally conductive lubricant. A pressure means, acting upon the flexible circuit board is directed to press the modules and the flexible circuit board toward the common cooling plate.
Whilst application to TAB technology is feasible, a problem with this arrangement is that no protection against mechanical failure is provided for TAB connections during manufacture of an electrical assembly. Furthermore, the flexible characteristic of the circuit board cannot be realised in such an electrical assembly.
Another approach, described by EPA, 116,396, provides a similar cooling system whereby a slab like heatsink material has raised pillars which protrude through holes in the flexible circuit board and make thermal contact with the flat undersides of integrated circuit modules mounted on the circuit board.
Good thermal contact to TAB devices cannot however be achieved in this manner. Furthermore, as described in the previous example, a common clamping format is suggested for maintaining good thermal contact between the heatsink and the modules by which means the flexible characteristics of the flexible electrical assembly are restricted.